<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app"></div>
</body>
<script src="https://unpkg.com/vue@next"></script>
<script>
const app=Vue.createApp({
    template:`
    <div>
        <div><input value="hello"  /></div>
        <div><input v-focus value="hello"  /></div>    
    </div>`,

})
app.directive('focus',{
        mounted(el) {
            el.focus();
        },
    })
    const vm=app.mount("#app")
</script>
</html>